1. Field of the Invention
The present invention relates to devices designed to absorb kinetic energy of a moving member.
2. Prior Art
In the prior art, various energy absorbing devices have been advanced, for example for automobile bumpers and steering wheel columns, and for absorbing energy of some air dropped items.
A unit which utilizes the buckling of members to provide a braking action for an air drop projectile is shown in the Franck et al. U.S. Pat. No. 3,528,530. A plurality of columns bend in the center to spread outwardly or mushroom out to provide a large diameter restraint for braking as the projectile enters the ground. There is no tension band which absorbs energy as the columns buckle.
Various columnar devices which will absorb energy while they are subjected to compression loads have been used in various applications including steering columns, as illustrated in U.S. Pat. No. 3,373,629 which shows an expanded metal section that buckles and absorbs energy. U.S. Pat. No. 3,587,787 shows an energy absorbing material, and mentions various prior art shock absorbing devices such as shear pins, nesting conical cylinders and honeycomb type shock absorbers.
U.S. Pat. No. 3,412,628 shows an energy absorbing unit that longitudinally crushes, but the energy appears to be absorbed by bending members rather than inelastic elongation of any tension bands. A crushable tube used as an energy absorber for a bumper is also shown in U.S. Pat. No. 3,437,367.
Thus, while certain energy absorbers have been shown in the prior art, devices that are simple to manufacture, low in cost, and which will absorb a substantial amount of energy while limiting the maximum loads imposed on the support structure are still sought. Further, devices which will take some eccentric loading are needed.